This is a leak, feel free not to believe what I say but I have some confirmed details from a couple of sources regarding the end of Bfa and the expansion after that. I will delete this post if it gets too much attention.
First things first, 8.3 won't be about old gods or the shadowlands. I will be all about what will be know as the great "battle for azeroth", a big conflict between both factions resulting in a completely ruined Azeroth. Both Orgrimmar and Stormwind will be heavily bombarded, few quite important characters will die and so on.
The next expansion will take place 5 years after Bfa and will be about healing and building a new, peaceful Azeroth. The expansion will be called "World of Warcraft: Awakenings" (If Legion and bfa names weren't stupid enough) and it will be like a second Cataclysm but better. It is now the perfect opportunity for the story to introduce new characters and potential new villains. As for gameplay, Blizzard is willing to take some risks this time with a level squish and a very ambitious world reborn. As for other key features, there will be a new, and expected mail wearing class: "tinker" with 3 specs (tank, dps and a melee healer?) available for humans, dwarves, gnomes, goblins, belfs, orcs and a few allied races if I remember correctly.There will be some signficant class changes.
Only two new zones will be added this expansion and both are being designed around flying: "Dragon Isles" (old god and dragon themed landmass) and a new and huge version of Caverns of time called "Edge of time" ( a huge, quite vertical and maze-like landmass composed of some rocks floating in space, something really different ). The rest of the work will be on the old world with mostly new or revamped questlines. The goal for this revamp is to make Azeroth fell relevant to both new and capped characters. This will be done in many ways ranging from Interesting treasures, world quests to AI encounters, new faction system and all sorts of events. They are also looking in making character progression relevant. Many of the past expansions assets will also help a lot in rebuilding the world. The first raid tier will be about the infinite dragonflight.
Now, the level squish. All current characters levels will be squished to 60, with 70 being the definitive level cap. Heilrooms are being removed. From 1-70 you can level in the new Azeroth. At level 30,you will be sent to Edge of time if you decide to level in past expansions (At 30: tbc,wrath 40:cata, mop 50:wod, legion or bfa) and at level 65 you will chose to level in one of the 2 new zones. There will also be a Suramar-like experience somewhere deep in the past. Starter edition cap will be increased to 40 and Blizzard will advertise this as Wow becoming free to play, kinda.
Another crazy feature that is being worked on is a Battle Royale experience, available at a very low level with its own progression system and it will be non-canon, meaning that it is open for all sorts of crazy stuff and ideas. It will use the full potential of island expedition tech combined with other popular battle royale game features.
This is all i know, Blizzard is willing to go crazy next expansion but the most important thing is that Classic wow will come out and they will have that if something goes wrong and the release date for it will be announced in a couple of weeks. 9.0 will be announced at Blizzcon as usual.